Biologists
have studied and observed polar bears in Canada's western Hudson
Bay for years. Important data has come from this research,
such as how long the polar bears spend on the shores of Hudson Bay
annually and how much of a decline of ice there is in the bay. Now,
researchers have answered the question regarding how long the polar
bears have before global warming ends
their existence.

Biologist
Andrew E. Derocher of the University of Alberta, along with Dr. Peter
K. Molnar and other colleagues, have found that the polar bear
population in western Hudson Bay could die out in approximately 25 to
30 years.

Derocher
and his colleagues came to this conclusion after discovering some
other startling data. The polar bears in this area have been losing
more than 20 pounds per decade, their body mass has been declining,
females have lost 10 percent of their body length, they've been
forced to spend an extra week per decade onshore, and the
overall population has decreased from 1,200 to 900 in three decades.
Most of the population drop occurred over this past decade. In
addition, mating habits have changed under recent
climatic conditions which could hinder the survival of the
polar bears.

"We
developed a model for the mating ecology of polar bears," said
Molnar. "The model estimates how many females in a population
will be able to find a mate during the mating season, and thus get
impregnated."

Molnar
further explained that male polar bears find mates by tracks in the
ice, and when a female is leaving tracks in mating condition, the
male will follow. As the climate warms, ice is lost and more time
onshore leads to a decrease in body mass and health, which results in
less reproduction.

The
tip of the iceberg was when projected sea ice declines were
observed due
to global warming, which led Derocher, Molnar and their
colleagues come to the conclusion that polar bears in the western
Hudson Bay would be doomed in 25 to 30 years. Polar bears' health
depend very much on the time spent on on sea ice hunting seals, and
with a decline in sea ice, they cannot hunt and their health is put
in jeopardy. Derocher said all it would take is "several
straight years of low sea ice conditions -- such as the current year
-- which could force the bears onshore for more than five months a
year, leading to a sharp decline in in the bears' physical condition
and the female's inability to gestate cubs."

Derocher
and his colleagues wrote a research
paper on their Hudson Bay polar bear population findings,
which was published in Biological
Conservation.
Derocher laid out the best and worst case scenarios for the
population based on the data collected from Hudson Bay.

"The
worst-case scenarios are that this population could be gone within
the decade," said Derocher. "A more optimistic scenario
would say that we'll bounce between good years and bad years for
several decades to come. Everything that we can see about the
sea ice in western Hudson Bay suggests that it's going to
disappear sooner rather than later."

Some
biologists have suggested that the polar bears in this area could be
saved by adapting to life on land and eating goose eggs, but Derocher
argues that this isn't a stable food source. While polar bears do eat
goose eggs, this would only help them out for a day or two of lost
time on the sea ice. Also, once polar bears ate all of the goose
colony's eggs in the Churchill area, the goose population would die
out, and the polar bears would face problems in food shortages on
land as well.

This
research has led
biologists to worry about other polar bear populations
around the world such as those in the Davis Strait area between
Canada and Greenland and those in the Chukchi Sea between Alaska and
Russia. According to Derocher, polar bears in these areas are
vulnerable to climate change as well.

"The
first paper I coauthored about this came out in 1993 and at that time
I was still under the impression that even though climate change was
a concern, it was really going to be for the next generation of
biologists -- or perhaps even the one after that -- to deal with the
issue," said Derocher.

"I've
been really shocked at the rate of change, and I've probably been
even more shocked at the lack of concern of political bodies to deal
with this. It's been quite disheartening to watch this lack of
interest, and I think it's really unfortunate that people don't
understand that we have a limited time to deal with this issue if we
want to save the polar bears."

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